#include <iostream>
using namespace std;

int main ()
{
    int x,y=0;
    cin >> x;
    if (x==1)
    {
        cout << x-1;
        return 0;
        system ("pause > void");
    }
    if (x>1 && x<=10000)
    {
        for (int z=1;z<=x;++z)
        {
            y+=z;
        }
    }
    if (x<1 && x>=-10000)
    {
        for (int z=x;z<=1;++z)
        {
            y+=z;
        }
    }
    cout << y;
    system ("pause > void");
}

Edited by author 10.11.2013 23:05

For x=1 your output is wrong; why do you print x-1?

ok,THX)) if x=1,cout x or 1

Edited by author 15.11.2013 18:51